Signs and symptoms of male breast cancer can include:
- A painless lump or thickening in your breast tissue
- Changes to the skin covering your breast, such as dimpling, puckering, redness or scaling
- Changes to your nipple, such as redness or scaling, or a nipple that begins to turn inward
- Discharge from your nipple
When to see a doctor
Make an appointment with your doctor if you have any persistent signs or symptoms that worry you.
It's not clear what causes male breast cancer.
Doctors know that male breast cancer occurs when some breast cells divide more rapidly than healthy cells do. The accumulating cells form a tumor that may spread (metastasize) to nearby tissue, to the lymph nodes or to other parts of the body.
Where breast cancer begins in men
Everyone is born with a small amount of breast tissue. Breast tissue consists of milk-producing glands (lobules), ducts that carry milk to the nipples, and fat.
During puberty, women begin developing more breast tissue, and men do not. But because men are born with a small amount of breast tissue, they can develop breast cancer.
Types of breast cancer diagnosed in men include:
- Cancer that begins in the milk ducts (ductal carcinoma). Nearly all male breast cancer is ductal carcinoma.
- Cancer that begins in the milk-producing glands (lobular carcinoma). This type is rare in men because they have few lobules in their breast tissue.
- Cancer that spreads to the nipple (Paget's disease of the nipple). Rarely, male breast cancer forms in the milk ducts and spreads to the nipple, causing crusty, scaly skin around the nipple.
Inherited genes that increase breast cancer risk
Some men inherit abnormal (mutated) genes from their parents that increase the risk of breast cancer. Mutations in one of several genes, especially a gene called BRCA2, put you at greater risk of developing breast and prostate cancers.
These genes normally make proteins that keep cells from growing abnormally — which helps prevent cancer. But mutated genes aren't as effective at protecting you from cancer.
Meeting with a genetic counselor and undergoing genetic testing can determine whether you carry gene mutations that increase your risk of breast cancer — and if you can pass this gene along to your children, both boys and girls. Discuss the benefits and risks of genetic testing with your doctor.
Factors that increase the risk of male breast cancer include:
- Older age. Your risk of male breast cancer increases as you age. The peak incidence of male breast cancer occurs between the ages of 68 and 71.
- Exposure to estrogen. If you take estrogen-related drugs, such as those used as part of a sex-change procedure or for hormone therapy for prostate cancer, your risk of breast cancer is increased.
- Family history of breast cancer. If you have a close family member with breast cancer, you have a greater chance of developing the disease.
- Klinefelter's syndrome. This genetic syndrome occurs when a boy is born with more than one copy of the X chromosome. Klinefelter's syndrome causes abnormal development of the testicles. As a result, men with this syndrome produce lower levels of certain male hormones (androgens) and more female hormones (estrogens).
- Liver disease. Certain conditions, such as cirrhosis of the liver, can reduce male hormones and increase female hormones, increasing your risk of breast cancer.
- Obesity. Fat cells convert androgens into estrogen. A higher number of fat cells in your body may result in increased estrogen and higher risk of breast cancer.
- Radiation exposure. If you've received radiation treatments to your chest, such as those used to treat cancers in the chest, you're more likely to develop breast cancer later in life.
- Testicle disease or surgery. Having inflamed testicles (orchitis) or surgery to remove a testicle (orchiectomy) can increase your risk of male breast cancer.